Centrifuges



March 14, 1967 E. v. JUNG ETAL CENTRIFUGES 2 Sheets-Sheet 1 Filed July17, 1964 E. V. JUNG ETAL arch 14, 1967 CENTRIFUGES 2 Sheets-Sheet 2Filed July 17, 1964 United States Patent O 3 claims. icl. 233-10) Theinvention relates to discontinuou'sly operating centrifuges and has forits object to facilitate removal of the centrifuged pulp from thecentrifuge drum rotating about a vertical spindle. For this purpose thecentrifuge is provided with a scraper for separating the pulp after thishas been deposited, by the centrifugal action, on the inside of the drumin the form of a hollow cylinder, the pulp after separation escapingthrough outlet openings in the bottom of the drum. The scraper isoperated yby means of a rotatably and/or displaceably mounted rod to thelower end of which the scraper is secured.

In centrifuging pulp of a baking nature centrifug'es of the kind statedabove have the disadvantage that the bottom openings are rapidly clogged-fby the excavated pulp, for which reason the drum must ybe cleanedmanually with accompanying shut-downs. It has been proposed previouslyto obviate these diiculties by subjecting the separated pulp, during thewhole or a part of the excavating process, to the action of compressedair, the air and the pulp then forming a suspension which is dischargedvery rapidly through the bottom openings. Devices of this kind arelknown wherein the compressed air is caused to flow out through airnozzles mounted on the scraper or on a member associated With thescraper and connected through a ilexible hose to a compressed airconduit located outside the drum. However, this device has severaldisadvantages. Among -other things the flexible hose is exposed to hardwear. Furthermore, this device renders it diflicult to cover in orencase adequately the centrifuge drum which is desirable, i.e. forprotecting the centrifuged pulp from being contaminated. Thesedisadvantages yare obviated according to the present invention by thecompressed lair being supplied to the air nozzles through a longitudinalpassage provided inside the operating rod. Thanks to this arrangementthe centrifuge drum together with the scraper secured to the lower endof tne operating rod may be enclosed in a casing completely covering thecentrifuge at the top and on the sides, and the necessary sealing may beprovided about the rod in its passage opening in the casing.

The invention will `be described in greater detail with reference to theaccompanying drawings. FIG. 1 is a vertical view, partly in section, ofa centrifuge provided with a device for supplying compressed air to theinterior of the drum in accordance with the invention.` FIG. 2 shows, ona larger scale, the tube structure wherein the operating rod isrotatably and displaceably mounted, and also a slide valve device forsupplying compressed air to the air passage provided centrally in theoperating rod.

The centrifuge drum 1 is mounted with its spindle 2 and driving motor 3on a frame consisting substantially of a girder system 5 arranged onlegs 4. The drum 1 has a cover 6 and a bottom 7 which latter hasopenings 8 provided centrally therein. These openings 8 form outl-etsfor the pulp separated by means of the scraper, which pulp has depositedduring the centrifuging process on the inside of the drum in the form ofa hollow cylinder 9. The loperating rod 10 is rotatably and displaceablymounted in known manner in a tube 11 which is secured at its top to thegirder 5 and at its bottom to the upper end wall 12 of a cylindricalcasing 13 enclosing the centrifuge drum and the excavating device, thetube being ice secured to said end wall by means of a socket 14encircling the lower end of the pipe 11. The excavating device consistsof a scraper 15 which is rigidly secured to the lower end of the rod 10by means of an arm 16, said rod passing through the end wall 12. Theupper end 17 of the operating rod 10 is threaded and adapted to bedisplaced axially `by means of a nut which is screwed on to said part 17and can be caused to rotate by means of a motor 18. During its movementthe operating rod is guided by means of a pin and groove connectioncomprising a pin 19 mounted on the rod and a groove 20 provided 'in thetube 11, 4said groove substantially extending axially but being bent ordiverted laterally -at its upper end. In displacing the operating roddownwards from the position shown in FIG. l, the rod will first berotated at the same time as it is moved downwardly, in so doing thescraper 15 is swung in under the cover 6 to the position indicated bychain-dotted lines, the scraper thus cutting its way into the pulpcylinder on the inside of the drum 1. Upon further movement downwards ofthe operating rod the pulp cylinder is excavated axially until thescraper arrives into its lowermost position when the whole pulp cylinderhas been removed.

In order to facilitate removing of the pulp from, the dmm means ar-eprovided for the supply of compressed air to a nozzle 21 disposed at thelower end of the arm 16 carrying the scraper and connected through apipe 22 to a passage 23 provided centrally in the operating rod, whichpassage may Ibe connected in turn to a compressed air conduit 24 'bymeans of a valving device controlled :by the rod. As will be best seenfrom FIG. 2, the compressed air conduit 24 is connected to a hole 25 inthe lower part 26 of the tube enclosing the operating rod, said holecommunicating with a pressure chamber 27 arranged on the inside of thetube part 26. This pressure chamber is sealed against the rod and thetube part 26 by two Isealing rings 28. By means of a cylindrical sleeve29 inserted into the chamber the sealing rings .are kept apart andpressed against the edges of the end portions 30 of the sleeve, in whichportions holes 31 are provided. The central air passage 23 is adapted tocommunicate with said pressure chamber 27 through a bore 32 extendingradially from the upper end of the passage.

During the longitudinal movement of the operating rod it functions as aslide valve to control the connection between the compressed air conduit24 and the central passage 23 in such manner as to open `and close theair inlet in certain axial positions of the scraper, which aredetermined by the relative position of the pressure chamber 27 and the'bore 32 and by the axial extent of the pressure chamber. Thearrangement is suitably such that compressed air is supplied to thenozzle 21 when the scraper 1S moves through the lower part of the drum.The air nozzle is arranged in such a way that the pulp separated #by thescraper is affected by the outowing air and is caused to escape throughthe outlet openings 8 in the ybottom of the drum.

What is claimed is:

1. In a centrifuge, in combination, a rotatable centrifuge drum, ascraper for excavating pulp deposited on the inside of the drum duringoperation, means causing said scraper t-o carry out a radial and anaxial excav-ating movement in said drum including a rotatably driven andaxially slidable elongated rod carrying said scraper, said drum havingoutlet openings in the bottom thereof, a compressed air nozzle arrangedon the scraper, said rod having a longitudinal passage providedinteriorly ofy said rod and communicating with said nozzle, means forsupplying compressed air to the nozzle to cause pulp excavated by saidscraper to be discharged through said outlet openings, thelast-mentioned means comprising a stationary compressed air 4supplyconduit, and means defining a slide valve comprising said rod operated-by the said axial movement of the rod to control passage of air betweensaid stationary air supply conduit and said longitudinal passage toapply compressed air to the nozzle in predetermined axial positions ofthe scraper.

2. In a centrifuge according to claim 1, in which said slide valvecomprises a tubular member circumferentially of said rod extendingaxially thereof at least a limited axial extent thereof, said tubularmember defining a pressure chamber circumferentially of said rod,communicating with said stationary conduit, said rod comprising a secondpassage communicating between the exterior of said rod and saidlongitudinal passage, whereby when said rod moves to a given axialposition in which said second passage is in communication with saidchamber compressed airis applied to saidk nozzle.

3. vIn a centrifuge according to claim 2, in which said chamber isdisposed in a position in which said nozzle is 4 rendered effective ataxial positions during which said scraper is moving axially through alower part of said drum thereby to'blow out excavated pulp out of saidopenings.

References Cited by the Examiner UNITED STATES PATENTS 1,048,905 12/1912Sperry 210-377 X 1,704,053 3/1929 Miller 285-190 X 2,056,885 10/1936Pecker 210--375 2,590,787' 3/1952 Nickles 285-190 X 2,953,250 9/1960lung et al. 233410 X FOREIGN PATENTS 250,155 2/1963 Australia.

M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner.

1. IN A CENTRIFUGE, IN COMBINATION, A ROTATABLE CENTRIFUGE DRUM, ASCRAPER FOR EXCAVATING PULP DEPOSITED ON THE INSIDE OF THE DRUM DURINGOPERATION, MEANS CAUSING SAID SCRAPER TO CARRY OUT A RADIAL AND AN AXIALEXCAVATING MOVEMENT IN SAID DRUM INCLUDING A ROTATABLY DRIVEN ANDAXIALLY SLIDABLE ELONGATED ROD CARRYING SAID SCRAPER, SAID DRUM HAVINGOUTLET OPENINGS IN THE BOTTOM THEREOF, A COMPRESSED AIR NOZZLE ARRANGEDON THE SCRAPER, SAID ROD HAVING A LONGITUDINAL PASSAGE PROVIDEDINTERIORLY OF SAID ROD AND COMMUNICATING WITH SAID NOZZLE, MEANS FORSUPPLYING COMPRESSED AIR TO THE NOZZLE TO CAUSE PULP EXCAVATED BY SAIDSCRAPER TO BE DISCHARGED THROUGH SAID OUTLET OPENINGS, THELAST-MENTIONED MEANS COMPRISING A STATIONARY COMPRESSED AIR SUPPLYCONDUIT, AND MEANS DEFINING A SLIDE VALVE COMPRISING SAID ROD OPERATEDBY SAID AXIAL MOVEMENT OF THE ROD TO CONTROL PASSAGE OF AIR BETWEEN SAIDSTATIONARY AIR SUPPLY CONDUIT AND SAID LONGITUDINAL PASSAGE TO APPLYCOMPRESSED AIR TO THE NOZZLE IN PREDETERMINED AXIAL POSITIONS OF THESCRAPER.